I've just come across the fact that QF is beginning a nonstop service between Sydney and Johannesburg, five times a week (leaving Perth-Johennesburg to SA). It must be one of the longest routes.
Another route that is not the longest by any means, but I find quite fascinating is the QF/AR joint venture from Buenos Aires to Sydney via Auckland. It used to stop at Rio Gallegos(Argentina) on the way out, but I've noticed that stop has been withdrawn altogether.
It may be just part of the legend, but it was said that at the start of AR's service (mid 80's?) a surveillance plane used to take off a little afterwards to follow the AR's 747 to spot where it went down just in case it didn't make it to New Zealand!! Oops, I'm drifting away from topic, sorry!!